Sudden cardiac arrest (SCA), also known as sudden cardiac death, is when the heart suddenly and unexpectedly stops beating as a result of an arrhythmia. When this occurs, blood stops flowing to the brain and other vital organs. SCA usually causes death if not treated in minutes.
SCA is not the same thing as a heart attack. A heart attack is a problem with blocked blood flow to a part of the heart muscle. In a heart attack, the heart usually does not suddenly stop beating. SCA, however, may happen during recovery from a heart attack.
People with heart disease have a higher chance of having SCA. But most SCAs happen in people who appear healthy and have no known heart disease or other risk factors for SCA.
Signs & Symptoms
Usually, the first sign of sudden cardiac arrest is loss of consciousness, which is similar to fainting. At the same time, breathing often stops and no heartbeat (or pulse) can be felt. Some people may first notice that they have a racing heartbeat or feel dizzy or lightheaded just before they faint.
Ninety-five percent of people who have SCA die from it, most within minutes. SCA requires immediate treatment with a device called a defibrillator, which delivers an electrical shock to the heart. Successful defibrillation restores normal rhythm to the heart. Defibrillation must be provided within minutes after SCA to avoid permanent damage to the body and brain and to prevent death. With every minute of delay in providing defibrillation, the chances of surviving SCA drop rapidly. People experiencing SCA should be given cardiopulmonary resuscitation (CPR) until they can be treated with a defibrillator.
Special defibrillators called automated external defibrillators (AEDs) can be used by untrained bystanders in an emergency. AEDs are becoming increasingly available at public places, such as airports, office building, and shopping centers. People who survive SCA may need an implantable cardioverter defibrillator to help prevent death if another SCA happens.Beta blocker drugs also help reduce the chance of death from SCA in people with known heart disease. Heart healthy lifestyle choices may lower people's chances for SCA.
Source: "Heart and Vascular Diseases." Diseases and Conditions Index. The National Heart, Lung, and Blood Institute. The National Institutes of Health.